Page 603 Design and Analysis of Pelton Wheel Bucket K.Chandra Sekhar Department of Mechanical Engineering, SISTAM College, JNTUK, India. P.Venu Babu Department of Mechanical Engineering, SISTAM College, JNTUK, India. ABSTRACT Pelton turbines are hydraulic turbines which are widely used for large scale power generation. A micro hydelpelton turbine is miniature model of actual pelton turbine which can be used for small scale power generation. This type of turbines converts potential energy of water at height into kinetic energy by allowing the water to fall freely on the pelton runner. This water impact provides necessary torque required for the rotation the runner by overcoming its inertia forces. The rotation of runner develops a mechanical energy which is coupled to the alternator which converts it into electrical energy. The project shows the analysis of the Pelton wheel bucket modelled using CATIA V5 software. The material used in the manufacture of pelton wheel buckets is studied in detail and these properties are used for analysis. The bucket is analyzed using ANSYS Workbench 15.0 .The bucket geometry is analyzed by considering the force and also by considering the pressure exerted on different points of the bucket. Structural analysis was carried out with two different meshes and also six different materials such as Grey Cast Iron; E-glass Fiber; AISI 1018 Steel; CA6nm Steel; Al Alloy; Ti6Al . The best combination of parameters like Von misses Stress and Equivalent shear stress, Deformation, shear stress and weight reduction for turbine bucket were done in ANSYS software. Grey cast iron has more factor of safety, reduce the weight, increase the stiffness and reduce the stress and stiffer than other material. With this analysis we can determine the lifetime and the strength of pelton turbine. 1. INTRODUCTION The Pelton wheel is an impulse type water turbine. It was invented by Lester Allan Pelton in the 1870s. The Pelton wheel extracts energy from the impulse of moving water, as opposed to water's dead weight like the traditional overshot water wheel. Many variations of impulse turbines existed prior to Pelton's design, but they were less efficient than Pelton's design. Water leaving those wheels typically still had high speed, carrying away much of the dynamic energy brought to the wheels. Pelton's paddle geometry was designed so that when the rim ran at half the speed of the water jet, the water left the wheel with very little speed; thus his design extracted almost all of the water's impulse energy—which allowed for a very efficient turbine. Fig 1.1 Pelton wheel impulse type water turbine 1.1Points to remember for Pelton Turbine: (i) The velocity of the jet at inlet is given by Where = co-efficient of velocity =0.98 or 0.99. H= Net head on turbine (ii) The velocity of when (u) is given by Where = speed ratio. The value of speed ratio varies from 0.43 to 0.48 (iii) The angle of deflection of the jet through the buckets is taken at 165 o if no angle of deflection is given. (iv) The mean diameter or the pitch diameter D of the pelton turbine is given by
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Page 603
Design and Analysis of Pelton Wheel Bucket
K.Chandra Sekhar
Department of Mechanical Engineering,
SISTAM College, JNTUK, India.
P.Venu Babu
Department of Mechanical Engineering,
SISTAM College, JNTUK, India.
ABSTRACT
Pelton turbines are hydraulic turbines which are
widely used for large scale power generation. A micro
hydelpelton turbine is miniature model of actual pelton
turbine which can be used for small scale power
generation. This type of turbines converts potential
energy of water at height into kinetic energy by
allowing the water to fall freely on the pelton runner.
This water impact provides necessary torque required
for the rotation the runner by overcoming its inertia
forces. The rotation of runner develops a mechanical
energy which is coupled to the alternator which
converts it into electrical energy. The project shows the
analysis of the Pelton wheel bucket modelled using
CATIA V5 software. The material used in the
manufacture of pelton wheel buckets is studied in
detail and these properties are used for analysis. The
bucket is analyzed using ANSYS Workbench 15.0 .The
bucket geometry is analyzed by considering the force
and also by considering the pressure exerted on
different points of the bucket. Structural analysis was
carried out with two different meshes and also six
different materials such as Grey Cast Iron; E-glass
Fiber; AISI 1018 Steel; CA6nm Steel; Al Alloy; Ti6Al .
The best combination of parameters like Von misses
Stress and Equivalent shear stress, Deformation, shear
stress and weight reduction for turbine bucket were
done in ANSYS software. Grey cast iron has more
factor of safety, reduce the weight, increase the
stiffness and reduce the stress and stiffer than other
material. With this analysis we can determine the
lifetime and the strength of pelton turbine.
1. INTRODUCTION
The Pelton wheel is an impulse type water turbine. It
was invented by Lester Allan Pelton in the 1870s. The
Pelton wheel extracts energy from the impulse of
moving water, as opposed to water's dead weight like the
traditional overshot water wheel. Many variations of
impulse turbines existed prior to Pelton's design, but
they were less efficient than Pelton's design. Water
leaving those wheels typically still had high speed,
carrying away much of the dynamic energy brought to
the wheels. Pelton's paddle geometry was designed so
that when the rim ran at half the speed of the water jet,
the water left the wheel with very little speed; thus his
design extracted almost all of the water's impulse
energy—which allowed for a very efficient turbine.
Fig 1.1 Pelton wheel impulse type water turbine
1.1Points to remember for Pelton Turbine:
(i) The velocity of the jet at inlet is given by
Where = co-efficient of velocity =0.98 or 0.99.
H= Net head on turbine
(ii) The velocity of when (u) is given by
Where = speed ratio. The value of speed ratio varies
from 0.43 to 0.48
(iii) The angle of deflection of the jet through the
buckets is taken at 165o if no angle of deflection is given.
(iv) The mean diameter or the pitch diameter D of the